When comparing aria2 vs WebTorrent Desktop, the Slant community recommends aria2 for most people. In the question“What are the best Torrent clients?”aria2 is ranked 4th while WebTorrent Desktop is ranked 7th. The most important reason people chose aria2 is:

Has support for lots of download protocols including BitTorrent, Metalink, HTTP, HTTPS and FTP.

Pros

Pro

Supports multiple download protocols

Has support for lots of download protocols including BitTorrent, Metalink, HTTP, HTTPS and FTP.

Pro

Small memory footprint

Due to aria2 being a CLI only tool it uses very little memory.

Pro

Free and open source

Pro

Remote control over simple standartized RPC

XML or JSON-based RPCs can be used to control aria2 remotely with both APIs completely documented. Simplest client that uploads torrent to be downloaded is 3 Python lines long (no 3rd-party libraries, only stdlib).Run aria2c --help=#rpc to see more.

Pro

Third parties offer a clean web interface

Some web interfaces consist of pure HTML+JS, no server-side needed (except aria2c of course). It uses the same RPC that can work even over WebSockets.

Pro

Streaming supported

Before the torrent is complete, you can stream the video and audio. It even supports seeking - it prioritizes the current location instead of always going in sequential order.